Lutein from Tagetes erecta L. is a purified extract obtained from marigold, which is extracted from the petals of marigold flowers. Lutein is chemically 3R,3’R,6’R-βε-carotene-3,3’-diol, which is a member of a group of pigments known as xanthophyll. It is used as a food colouring agent and nutrient supplement in a wide range of baked goods and baking mixes, beverages and beverage bases, breakfast cereals, chewing gum, dairy product analogs, egg products, fats and oils, frozen dairy desserts and mixes, gravies and sauces, soft and hard candy, infant and toddler foods, milk products, processed fruits and fruit juices, soups and soup mixes in levels ranging from 2 to 330 mg/kg.1
Marigold flower (Tagetes erecta L. Family Compositae) represents a rich source of lutein. It is grown for business purposes in Mexico, Peru, Ecuador, Spain, India or China. Dried Marigold flowers contain 0.1–0.2% dry matter of carotenoids, out of which 80% are lutein diesters. By the extraction of dried and ground flowers, a non-polar oleoresin extract is acquired.2 The recent evidence suggests that lutein is one of the abundant carotenoids in the diet and it possesses strong antioxidant capacity and may be useful in reduction of incidence of cancer.3
The xanthophylls, a major group of carotenoids, primarily include astaxanthin, b-cryptoxanthin, canthaxanthin, lutein, and zeaxanthin.4 Unpredicted drug interactions have led to severe adverse effects or treatment failures. Many of these interactions involve the inhibition or induction of drug-metabolising cytochrome P450 (CYP) enzymes. Similarly, dietary supplements or nutrients may be inhibitors or inducers of CYP enzymes and influence the pharmacokinetics of any co-administered drugs. There are few reports about interactions between drug-metabolising enzymes and astaxanthin, b-cryptoxanthin, canthaxanthin, lutein, and zeaxanthin.5 the aim of the present study was to find the effect of lutein isolated from Tagetes erecta L on cytochrome P450 isoform CYP3A4.
MATERIALS AND METHODS
Chemicals and Extract
Potassium phosphate buffer, CYP450 reagent, 7-Benzyloxy-4-trifluoromethylcoumarin (BFC), Tris-HCl buffer. All the chemicals used were of analytical grade. Lutein extract was obtained from Synthite Industries Limited as gratis.
5-100 microgram concentrations of lutein, potassium phosphate buffer, CYP450reagent and substrate 7-Benzyloxy-4-trifluoromethylcoumarin (BFC) were added to a 96-well plate. The mixtures were pre - incubated for 20 min at room temperature. The reaction was started by a mixture of reconstituted substrate and NADP+ and incubated at room temperature for 30-60 min. The reaction was stopped by Tris-HCl buffer, pH 10.5. The fluorescent intensities of the products were measured by Perkin Elmer Enspire fluorescence reader using an excitation and emission wavelength of 405 nm and 460 nm, respectively.6 IC50 was calculated by plotting concentrations of lutein against the corresponding percent inhibition. All tests were done in triplicate and values were expressed as mean ± SEM.
In the present study, lutein extracted from marigold has demonstrated good inhibitory effect on CYP3A4. Results indicate the possibilities of herb-drug interaction if lutein is co-administered with the prescribed drugs that are metabolized by CYP3A4. Lutein is known for its antioxidant activity.7
The cytochrome P450 enzymes are the main players in Phase I metabolism and also involved in the oxidation and elimination of a wide array of xenobiotics such as drugs and toxins.8 A number of therapeutic agents such as quinidine, vinblastine, ergotamine, berberine, and colchicines synthetic agents such as nifedipine and diazepamare the main substrates of CYP3A4.9, 10 Many plant extracts are capable of inhibiting CYP3A4 activity.11, 12 Grapefruit and kava-kava are best examples for herbal drugs that can cause clinically important modulation in CYP3A4 activity.13, 14 Many other plants are also evaluated for their effect on CYP450 enzymes. The effect of P. amarus and P. emblica aqueous extracts on all CYP isoforms were weaker. In a previous study, extract of Centenella asiatica showed concentration-dependent inhibitory effect on CYP3A4 activities.15 Studies show that plant products such as asiaticoside and madecassoside have inhibitory effect on CYP3A4. Asiaticoside inhibited CYP3A4 with an IC50 value of 3 43.35 ± 29.35μ M.Madecassoside, inhibited CYP3A4 with IC50 = 453.32 ± 39.33μ M.Asiaticoside exhibited non-competitive inhibition of CYP3A4 Madecassoside also showed non-competitive inhibition of CYP3A4.16
The inhibition of cytochrome P450 metabolism by blended herbal products and vitamins has revealed that the extracts have a low to moderate capacity to inhibit the cytochrome metabolism.17 Similarly, studies on Cocktail inhibition assays for assessing the drug-drug, drug-botanical interactions and assessing the six major cytochrome P450 enzymes was conducted by Guannan and Jing Wan respectively.18, 19
Drug–drug interactions may be identified during drug development and approval, food–drug interaction and supplements–drug interaction should not be overlooked. Natural health products are being widely used. Many plant products are useful in diabetes mellitus, anxiety, cancer and many such health problems.20–23 Apart from an appraisal of product safety and effectiveness, attention should be paid to the potential that these product ingredients may interact with medications. In recent years, dietary carotenoids, especially xanthophylls, have attracted significant attention because of their activities as antioxidants and their roles in preventing cancer and age-related macular degeneration. Although around 40 carotenoids are ingested through a typical diet, only a few xanthophylls have been found in human tissues. There are few reports of inducible effects on CYP activities by the xanthophylls astaxanthin, b-cryptoxanthin, canthaxanthin,lutein, and zeaxanthin. However, their inhibitory effects on CYPs have rarely been investigated.5
Lutein obtained from marigold petals is of major commercial interest because of its use in functional food and cosmetics, as well as in pharmaceuticals. In conclusion, lutein extracted from Marigold exhibited a dose dependent inhibitory effect on CYP3A4. Results from this study provide information indicating the possibilities of herb-drug interaction if this extract is co-administered with the prescribed drugs that are metabolized by CYP3A4. Further in vivo study is needed to investigate whether these effects are clinically significant.